This invention relates to a cathodic protection device for combating and inhibiting corrosion in copper piping.
Metallic structures installed underground, on the ground, in water, or other wise in contact with an electrolytic medium are subject to corrosion due to a chemical reaction with non-metallic elements in the surrounding medium. The amount or degree of corrosion that takes place may be influenced by several factors such as the type of metal in the structure, the amount of impurities in the metal and the chemical nature of the nonmetallic medium.
When metal corrodes, it replaces hydrogen or another metal from a compound in the surrounding medium. The reactions take place simultaneously on the metal surface. In one reaction metal ions pass into solution and in the other hydrogen ions pass out of solution to form hydrogen gas. Since these two reactions cannot take place at the same point, there must be two kinds of areas on the metal surface: those which are anodic where metal dissolves, and those which are cathodic where hydrogen ions are discharged. Thus, for corrosion to take place a metal structure must have these similar areas, and the interface between a metal and its environment cannot be entirely homogenous. This principle is borne out by the fact that pure, almost perfectly homogeneous, metals have an extremely high resistance to corrosion, even when exposed to highly acidic solutions.
The basis for any electro-chemical treatment of corrosion is the electro-motive force series which is an arrangement of the elements in order of their dissolution tendencies. It must be recognized that this series is dependent on the electrolyte in use at the time of measurement. In other words, it may be said that every solution has its one electro-motive force series.
Water that flows through most piping systems usually have impurities containing various ions, and therefore acts as an electrolyte. Corrosive action may therefore take place on the inside surface of the pipe as described above when any one portion of the metallic pipe structure becomes anodic with respect to another part of the same pipe or with respect to some other object in the surrounding medium. During this electrolytic corrosive action, metal in the anodic areas of the structure is electro-chemically removed, and a weakening and eventually perforation of the piping results. It is well known that corrosive structures can be protected by attaching an expendable material that is anodic with respect to the structure so that material will be dissolved from the sacrificial anode rather than from the structure itself.
It is therefore an aim of my invention to provide an improved Cathodic System particularly adaptable for preventing corrosion in piping systems.
Prior U.S. Patents used in various types of pipe protection systems can be seen in the E. L. James et al, U.S. Pat. No. 2,556,089 for a Cathodic Protection Device in which a magnesium rod is mounted to extend from the pipe entering a hot water heater into the hot water heater. The Truitt et al, U.S. Pat. No. 4,713,159 now has a metal treatment bar in a pipe and the Dunn et al, U.S. Pat. No. 3,974,071 is a water conditioning device in which a scale and inhibiting rod is mounted in a link of pipe The Craft et al U.S. Pat. No. 3,448,034 mounts a stabilizing rod in a well casing as does the R. C. Buchan, U.S. Pat. No. 2,846,385 which prevents corrosion in wells. The H. E. Turnes et al, U.S. Pat. No. 3,406,110 is for a Cathodic Protection of Pipes in a cooling system in which rods are mounted in different positions and pipes are attached to threaded plugs for the insertion or removal of the protective rods. In the U.S. Pat. No. 3,342,712 to a O'Keefe, a water conditioning method has a pipe with a section inserted thereinto which holds a pair of removal sacrificial rods and the whole system is placed within a water line. The Van A. Mills, U.S. Pat. No. 1,705,197 is an electro-chemical means of protecting the interior of pipes from corrosion and has an enlarged pipe section inserted in the pipe line having a treatment portion lining the enlarged pipe section. The Latter U.S. Pat. No. 2,358,981 shows a corrosion preventing device placed in a water line adjacent a boiler The Sherman U.S. Pat. No. 3,445,370 is a corrosion prevention device for irrigation systems in which a Cathodic Device is bolted in a section of an irrigation pipe. The Fauth et al, U.S. Pat. No. 3,794,574 is a device for Cathodically protecting metal conduit systems in which sacrificial rods are placed in a large section of the pipe.
The Present invention is similar to these prior patents in that it uses a sacrificial anode to cathodically protect against pitting in a building's copper pipes by having a copper pipe section which is readily placed in the water line entering the building to form a part of the water line and has an incorporated sacrificial anode axially aligned in the pipe and held by brackets supporting a stiffening conductive rod supporting the sacrificial anodes and allowing one end of the anode to have an improved grounding system.